It’s interesting to contrast this correspondence with Dijkstra’s later advocacy of functional programming. I’ll quote a passage of a letter he wrote in 2001, which seems to agree with Backus:

> A fundamental reason for the preference [for functional programming] is that functional programs are much more readily appreciated as mathematical objects than imperative ones, so that you can teach what rigorous reasoning about programs amounts to.

Source: http://chrisdone.com/posts/dijkstra-haskell-java